DESCRIPTION (Applicant's abstract verbatim): The object of this Phase I proposal is to demonstrate feasibility of a gradient coil suitable for human head Magnetic Resonance Imaging (MRI) microscopy at fields from 1 to 8 T with substantially higher performance than is currently available. The coil will be capable of continuous field gradients in excess of 100 mT/m along the Z axis and similar pulse gradients along the X and Y axes with slew rates up to 400 T/m/s at improved efficiency. The gradient coil will be switchable between a configuration optimized for functional MRI (fMRI) using Echo Planar Imaging (EPI) and one optimized for high-gradient techniques such as high-resolution diffusion-weighted microscopy MRI (DWI). Compared to state-of-the-art head gradient coils, the novel force-canceled gradient coil will have more than twice the continuous gradient capability, 30 dB less acoustic noise, and reduced nerve stimulation at higher slew rates. The coil will enable a substantial improvement in image resolution and/or imaging time on MRI scanners by all manufacturers. DWI, fMRI, and ultra-fast 3D gradient-echo angiography techniques will become widely practical. DWI has shown promise in the detection of acute ischemia within minutes (hours before it is seen in T2-weighted images); and ultra-high-field DWI has demonstrated order-of-magnitude advantages in resolution in white matter and nerves, owing to the diffusion anisotropy of the myelin. High-field DW EPI permits complete brain scans in under 0.1 second with adequate resolution for real-time monitoring of brain function, but it is not currently generally practicable because of gradient coil limitations. PROPOSED COMMERCIAL APPLICATION: There are approximately 12,000 MRI systems installed world-wide, and annual MRI equipment sales are currently about $3B. The proposed gradient coil would permit substantially improved image resolution, reduced imaging time (hence, cost), and reduced patient distress for head imaging in most current systems at the relatively modest upgrade cost of about $180,000. Total upgrade market potential over the decade following completion of the Phase II easily exceeds $300M.